I have a question.

Okay. So, let's say you're looking at your average pea plant. And, following the rules of genetics as set out by Mendel, we know that if it's got one recessive gene for a trait, and one dominant gene for that same trait, the dominant one is the one we'll see.

Now, I'll interrupt a second and say that bio was never my subject. Chem was easy, and physics was a blast, but I only got through bio (the third time. Time one was a flop, and time two... well, I passed the tests, but I still wasn't able to really do the work) by memorizing a bunch of facts that didn't make much sense to me. (They made more sense once I took chem, and more again when I took physics. We teach high school science backwards.) So you'll correct me if I say anything devastatingly wrong.

Now, as I understand it, your chromosomes themselves just consist of a small number of nucleotides. So what makes a specific combination of nucleotides say "make this pea green" or "this one's gonna be a yellow pea" or even (in the case of extreme manipulation or random mutation) "purple all the way"?

For that matter, how does a pretty small difference in DNA make me a human, and outside we've got daisies? Or even a huge difference, every little detail different, how does it work to make things? How does it make sense?

I never understood that point. I just threw it back up on the tests, whatever I needed to know (the second and third years. The first year was a loss completely), and I've forgotten a lot of it, since I didn't really learn it properly the first (three) time(s) around.